California's deadliest current wildfire is getting larger, officials warn, despite thousands of firefighters battling it.
"Erratic winds" and dry conditions have caused the Carr fire to grow early on Sunday, firefighters said.
It is one of eight major wildfires currently burning in the state.
The fire, in the Shasta County in northern California, has killed six people so far, including two children and their great-grandmother.
Melody Bledsoe, 70, Emily Roberts, five, and James Roberts, four, died when they were caught in its path as they were about to evacuate their home in the town of Redding, about 150 miles (240km) north of Sacramento, on Thursday.
An unidentified fourth body was found in a burnt-out house on Sunday.
Two firefighters also lost their lives on Thursday. A third firefighter died battling the Ferguson fire, near Yosemite, on Sunday.
The Carr fire, which doubled in size overnight on Friday, was only 5.0 per cent contained by Sunday morning. It has already burnt more than 48,000 acres (194 sq km) of land and destroyed at least 500 structures.
It began on Monday. On Thursday it became a firestorm, jumping across the Sacramento River, according to news agency Reuters.
California department of forestry and fire protection (CalFire) chief Ken Pimlott told reporters they were "seeing fire whirls - literally what can be described as a tornado".
"This fire was whipped up into a whirlwind of activity" by gale-force winds, he said, "uprooting trees, moving vehicles, moving parts of roadways".
A total of 38,000 people have been evacuated from Shasta County. California's Governor Jerry Brown has declared a state of emergency in the area, as well as three others.
US President Donald Trump has approved federal aid for the counties.
The Carr is the largest of eight big fires burning in California, and 90 across the country, according to the National Interagency Fire Center.
There are currently 12,000 firefighters battling the flames across the state.
Wildfires are a common occurrence in California during the state's long, hot, dry summers.
However, experts say this has been the worst start to the fire season in 10 years - partly due to the 2012-2017 drought that killed off large amounts of vegetation, BBC reported.
UCLA climate scientist Daniel Swain told the Los Angeles Times much of the state's vegetation had reached "explosively dry" levels, Reuters reported.
In December, Governor Jerry Brown said devastating wildfires fuelled by climate change had become "the new normal", and that large fires "could happen every year or every few years".